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Strain improvement via chemical mutagen could impart traits with better enzyme production or improved characteristics. The present study sought to investigate the physicochemical properties of pullulanase produced from the wild Bacillus sp and the mutant. The pullulanases produced from the wild and the mutant Bacillus sp. (obtained via induction with ethyl methyl sulfonate) were purified in a-three step purification procedure and were also characterized. The wild and mutant pullulanases, which have molecular masses of 40 and 43.23 kDa, showed yields of 2.3% with 6.0-fold purification and 2.0% with 5.0-fold purification, respectively, and were most active at 50 and 40 °C and pH 7 and 8, respectively. The highest stability of the wild and mutant was between 40 and 50 °C after 1 h, although the mutant retained greater enzymatic activity between pH 6 and 9 than the wild. The mutant had a decreased Km of 0.03 mM as opposed to the wild type of 1.6 mM. In comparison to the wild, the mutant demonstrated a better capacity for tolerating metal ions and chelating agents. These exceptional characteristics of the mutant pullulanase may have been caused by a single mutation, which could improve its utility in industrial and commercial applications. [ABSTRACT FROM AUTHOR]